Amphibious vehicle

Abstract

A planing amphibious vehicle has at least one trim tab at its stern. A vehicle control system includes a mode change controller and a trim tab controller. The mode change controller informs the trim tab controller when a mode change event is taking place. The trim tab controller retracts the trim tabs if the mode change is from marine to land mode; and deploys the tabs if the change is from land mode to marine mode, to assist the vehicle in rising on to the plane. The controller may also retract the tabs if the vehicle reverses; and deploy the tabs if a change is made from reverse to forward motion. The vehicle control system may connect to actuators and sensors for retractable road wheels, which may use hydropneumatic struts. Safeguards against system faults and / or erroneous switch operation are included. Road wheel drive decouples are used; a marine drive decoupler may also be fitted.

Description

BACKGROUND OF THE INVENTION[0001]The present invention relates to an amphibious vehicle.[0002]Amphibious vehicles are inherently required to carry both road vehicle and marine vessel dedicated equipment. Hence, amphibious vehicles are generally heavier than boats of a similar size and power. This is particularly true in the case of planing amphibians, which require a relatively heavy wheel streamlining mechanism, such as retractable suspension or the like. In the case of an amphibious vehicle with open wheel arches, the drag exerted by the arches can be considerable and hence the overall hull drag is greater than for a conventional boat. This additional weight and drag make it difficult for the vehicle to rise onto the plane without initial deployment of trim tabs.[0003]Trim tabs are well known for marine vessels, and in particular planing boats, as means for controlling the trim and attitude of the vessel to compensate for changes in load, speed or sea conditions. Commonly these de...

AI Technical Summary

Benefits of technology

[0009]According to one aspect of the present invention there is provided an amphibious vehicle adapted for use on land and on water including a vehicle body, and at least one trim tab, for adjusting the trim of the amphibious vehicle when it is in a marine mode, connected to the vehicle body and movable relative to the vehicle body between a retracted position and any one of a range of operational positions, and a control

Problems solved by technology

Hence, amphibious vehicles are generally heavier than boats of a similar size and power.

In the case of an amphibious vehicle with open wheel arches, the drag exerted by the arches can be considerable and hence the overall hull drag is greater than for a conventional boat.

This additional weight and drag make it difficult for the vehicle to rise onto the plane without initial deployment of trim tabs.

For example, if the rear of the vessel is heavily loaded the bow will typically rise out of the water and lead to inefficient forward motion.

The system described in U.S. Pat. No. 5,113,780 is designed specifically for marine only vessels and is of limited benefit in the case of amphibious vehicles fitted with trim tabs.

The greatest risk of damage, in the case of amphibious vehicles, occurs during and after the transition from marine to terrestrial mode, whilst the engine is still switched on.

If the tabs remain in an operational position when the vehicle leaves the water, there is a significant risk that they may strike the ground at speed.

Similarly, reversing into an obstacle with the trim tabs deployed could damage the tabs, the actuators and the body of the vehicle.

Such a supply, however, is undesirable because the power source remains permanently connected to the circuit that it powers.

Hence, even a relatively small current drain from the retraction circuit could lead to a significant reduction in the life of the source.

Whilst a permanent current drain may be unlikely to arise as a result of poor design there is a significant probability that it could occur as a result of malfunction.

The risk of this is particularly high in marine vessels where the presence of water makes short circuits more likely.

It will also be appreciated that short circuits of this type also constitute a safety hazard.

However, this system is also designed specifically for marine only vessels and again is of limited benefit in the case of amphibious vehicles, for the reasons discussed above in relation to U.S. Pat. No. 5,113,780.

Images